The main reason I've been considering a switch is this: my experience with interactive development with Chez has been less than awesome.
haven't read the rest of the post, but i wonder if he considered using guile. guile+emacs+geiser has been providing me a pretty good experience
edit: should've read the entire thing
(To be fair, Guile Scheme has pretty decent support for interactive development. However, Guile + Geiser cannot do to stack traces what SBCL + SLIME can.)